JP2021024506A - Railway vehicle with sound absorption mechanism - Google Patents

Abstract

To efficiently absorb an in-cabin acoustic standing wave.SOLUTION: A sound absorption mechanism comprises: a punched micropore plate that has a plurality of punched micropores; a rigid plate that is arranged in the state of mutually facing the punched micropore plate and that reflects a sound transmitted through the punched micropore plate; and a plurality of side plates that are each connected to the punched micropore plate and the rigid plate and that keep a distance between the punched micropore plate and the rigid plate constant. A cube is composed of the punched micropore plate, the rigid plate and each of the plurality of side plates. The sound absorption mechanism is arranged in an antinode position of an acoustic standing wave within a cabin.SELECTED DRAWING: Figure 4

Description

The present invention relates to a railway vehicle with a sound absorbing mechanism having a sound absorbing mechanism that absorbs a standing sound wave in a passenger compartment.

In high-speed railway vehicles (hereinafter referred to as railway vehicles) represented by the Shinkansen (registered trademark), the noise inside the passenger cabin (hereinafter referred to as cabin noise) tends to increase as the operation speed increases and the power output increases. Therefore, various measures have been taken to suppress the increase in cabin noise and maintain comfort.

Room noise is roughly divided into air-borne noise and solid-borne noise. In general, the air propagating sound that is dominant at high frequencies can be reduced by increasing the sound insulation of the vehicle body, and the solid propagating sound that is dominant at low frequencies can be reduced by suppressing the vibration propagation of the vehicle body. Is. One example of enhancing the sound insulation of the former is shown in Patent Document 1. In an actual railroad vehicle, cabin noise is louder at lower frequencies than high frequencies, and it is difficult to sufficiently reduce it by simply increasing the thickness of the sound absorbing material, which leads to a reduction in cabin space. Therefore, Patent Document 2 discloses a method of absorbing cabin noise in a specific frequency band with a tubular structure of a specific length attached to an interior panel.

JP-A-2017-105228 Japanese Unexamined Patent Publication No. 2017-100637

The mechanism disclosed in Patent Document 1 has the effect of reducing cabin noise at a wide frequency range, but sufficiently lowers the standing wave peak in the cabin in the low frequency range and the middle frequency range (hereinafter referred to as low and middle frequency range). Ability is limited.

On the other hand, the mechanism disclosed in Patent Document 2 has the effect of absorbing room noise in a specific frequency band (including low and medium frequency bands), and it is possible to set a plurality of the specific frequencies. It is not designed to deal with the variation phenomenon in the vehicle, and when the variation phenomenon is large, it is considered that the sound absorption effect is limited due to the size limitation.

An object of the present invention is to efficiently absorb an acoustic standing wave in a cabin.

In order to solve the above-mentioned problems, the present invention is a railroad vehicle having a passenger compartment, in which a fine perforated plate having a plurality of fine perforations and the fine perforated plate arranged opposite to the fine perforated plate are provided. A sound absorbing mechanism including a rigid plate that reflects passed sound is provided, and the sound absorbing mechanism is arranged at a position on the antinode of an acoustic standing wave in the vehicle interior.

According to the present invention, it is possible to efficiently absorb the standing sound wave in the cabin.

It is sectional drawing of the plane intersecting with the longitudinal direction (traveling direction) of the railroad vehicle which concerns on embodiment of this invention. It is a sound pressure distribution diagram which shows a typical example of the sound pressure distribution of the acoustic standing wave generated in the passenger cabin of the railroad vehicle which concerns on embodiment of this invention. It is a block diagram which shows the basic structure of the sound absorption mechanism which concerns on Embodiment 1 of this invention, (a) is a sectional view of the sound absorption mechanism, (b) is a perspective view of a sound absorption mechanism, (c) is a sound absorption mechanism. It is a front enlarged view of the mechanism. It is sectional drawing of the main part of the railroad vehicle equipped with the sound absorbing mechanism which concerns on Embodiment 1 of this invention. It is a figure of the sound absorption mechanism which concerns on Embodiment 2 of this invention, (a) is the sectional view of the sound absorption mechanism which concerns on Embodiment 2 of this invention, (b) is the figure of Embodiment 2 of this invention. It is a front view of the said sound absorption mechanism. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 3 of this invention. It is a perspective view of the sound absorption mechanism which concerns on Embodiment 4 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 5 of this invention. It is a perspective view of the sound absorption mechanism which concerns on Embodiment 6 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 7 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 8 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 9 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 10 of this invention. FIG. 11 is a cross-sectional view of the sound absorbing mechanism according to the eleventh embodiment of the present invention, in which FIG. 11A is a cross-sectional view of the sound absorbing mechanism in which the fine perforated plate faces the traveling direction of the train, and FIG. Is a cross-sectional view of the sound absorbing mechanism facing in the direction opposite to the traveling direction of the train. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 12 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 13 of this invention. It is sectional drawing of the sound absorption mechanism which concerns on Embodiment 14 of this invention. FIG. 5 is a cross-sectional view showing an example of a sound absorbing mechanism according to a fifteenth embodiment of the present invention, which is configured by combining various fine perforated plates.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a surface intersecting the longitudinal direction (traveling direction) of the railway vehicle according to the embodiment of the present invention. In FIG. 1, the railroad vehicle structure 105 of the railcar 100 is arranged along the longitudinal direction (traveling direction) of the railcar 100 to form a floor surface, and the underframe 110 and the width direction of the underframe 110 (railroad vehicle 100). Side structures 120 installed at both ends in the longitudinal direction of the underframe 110, and wife structures (not shown) arranged at both ends in the longitudinal direction of the underframe 110, facing the underframe 110. It is composed of a side structure 120 and a roof structure 130 arranged at each upper end of the wife structure.

Inside the railroad vehicle structure 105, an interior panel 140, which is an inner wall of a passenger cabin (car compartment), is arranged. The interior panel 140 is composed of a side panel 142 which is a side wall of the guest room, a side ceiling panel 145 which is a part of the side wall of the guest room and a part of the ceiling wall, and a central ceiling panel 148 which is a ceiling wall of the guest room. The side panel 142 is arranged at a position inside the side structure 120 (inside the vehicle), and the side ceiling panel 145 and the center ceiling panel 148 are arranged at a position inside the roof structure 130. A luggage rack 150 is arranged on the upper part of the inside of the side structure 120. A stool (not shown) is arranged on the upper floor 112 of the underframe 110, and an underfloor duct 115 or the like is arranged under the upper floor 112.

A heat insulating sound absorbing material 180 is sealed between the railway vehicle structure 105 and the interior panel 140.

When the interior of the railroad vehicle 100 shown in FIG. 1 is targeted, a noise peak and its unique acoustic mode exist at a certain frequency determined by the air condition such as its shape, boundary conditions, and sound velocity, that is, in the cabin. There is an acoustic standing wave in. The point where the sound pressure amplitude of the acoustic standing wave is the smallest is called the node, and the point where the amplitude is the largest is called the antinode. The particle velocity distribution of the acoustic standing wave is the reverse of the positions of the antinodes and nodes of the sound pressure distribution.

Here, when the cabin noise is simply reduced by using a sound absorbing material, the wavelength of the sound becomes longer as the frequency becomes lower. Therefore, in order to obtain a sufficient sound absorbing effect, it is necessary to make the sound absorbing material thicker as the frequency becomes lower. is there. Increasing the thickness of the sound absorbing material leads to a reduction in the cabin space, and therefore there is a limit to the thickness of the sound absorbing material. In other words, there is a limitation in simply thickening the sound absorbing material, and other means are required to reduce the noise peak of the standing wave in the cabin in the low to medium frequency band where the sound absorbing material cannot be sufficiently absorbed.

Therefore, in the present embodiment, the noise in the railroad cabin in the low to medium frequency range is reduced by the sound absorbing mechanism including the fine perforated plate, and the noise reduction amount which is impossible with the simple sound absorbing material of the same thickness is realized. Is what you do.

FIG. 2 is a sound pressure distribution diagram showing a typical example of the sound pressure distribution of an acoustic standing wave generated in the passenger compartment of a railroad vehicle according to the embodiment of the present invention. In FIG. 2, the space in the passenger compartment surrounded by the interior panel 140 of the railroad vehicle 100 is divided into a plurality of bellies and a plurality of nodes. At this time, there are sound pressure vents in the plurality of luggage rack upper parts A, the underframe portion B, the ceiling center portion C, the cabin center portion D, and the plurality of luggage rack lower parts E, respectively. The plurality of luggage rack upper parts A and the plurality of luggage rack lower parts E are symmetrical with respect to the center of the cabin.

Here, in the present embodiment, in order to efficiently absorb the sound standing wave in the guest room without narrowing the guest room, the sound absorbing mechanism is installed at the abdominal position of the sound pressure in the guest room or at a position as close to the abdomen as possible.

For example, in each luggage rack upper part A, a sound absorbing mechanism is installed in the interior panel portion at the back of the luggage rack in the upper part of the luggage rack 150. The underframe portion B has an upper floor 112 and a lower floor (including the underfloor duct 115), and it is difficult to directly install the sound absorbing mechanism on the upper plate 112 due to problems such as clogging. As will be described later in the section 12, a sound absorbing mechanism facing the outside (outside the vehicle) is installed under the underfloor duct 115. In the ceiling central portion C, a sound absorbing mechanism can be installed on the central ceiling panel 148. It is difficult to install a sound absorbing mechanism in the central part D of the passenger cabin because the central portion D of the passenger cabin is on the aisle and hinders the passage of passengers. In each lower part E of the luggage rack, a sound absorbing mechanism can be installed on the upper part of the side panel 142 or on the lower surface of the luggage rack 150.

From the viewpoint of a position that is difficult for passengers to see from the upper part A to the lower part E of each luggage rack, the sound absorbing mechanism is located at the inner part of the luggage rack of each upper part A of the luggage rack and the lower part of the underfloor duct 115 of the underframe portion B. It is desirable to install. These two locations correspond to the upper part A of the luggage rack and the underframe portion B shown in FIG. 1, respectively. By arranging the sound absorbing mechanism at the antinode position of the sound pressure in the acoustic mode of a certain indoor standing wave frequency in the low to medium frequency range, it is possible to efficiently absorb the in-room acoustic standing wave without narrowing the cabin.

FIG. 3 is a configuration diagram showing a basic configuration of the sound absorbing mechanism according to the first embodiment of the present invention, (a) is a cross-sectional view of the sound absorbing mechanism, (b) is a perspective view of the sound absorbing mechanism, and (c). ) Is a front enlarged view of the sound absorbing mechanism.

In FIG. 3, the sound absorbing mechanism 4 includes a micro-perforated plate 1 having a plurality of micro-perforated plates 10, a rigid plate 2 arranged behind the micro-perforated plates 1 and reflecting sound passing through each of the micro-perforated plates 1, and micro-perforated plates. It is configured as a box (cube) provided with a plurality of side plates 3 connecting the plate 1 and the rigid plate 2 and forming an air layer (back air layer) inside the side plates 3. The fine perforated plate 1 is arranged inside the railway vehicle 100, for example, and the rigid plate 2 is arranged so as to face the outside of the railway vehicle 100. The fine perforated plate 1 and the rigid plate 2 are connected to each side plate 3 and arranged at a constant distance from each other.

The role of each side plate 3 is to keep the distance between the fine perforated plate 1 and the rigid plate 2 constant, and the side plate 3 does not have to be plate-shaped as long as it plays that role. For example, it may be rod-shaped or strip-shaped. Hereinafter, the structures having a role of keeping the distance between the fine perforated plate 1 and the rigid plate 2 constant are collectively referred to as a side plate 3.

The sound absorbing mechanism 4 is a Helmholtz type sound absorbing device, and can be modeled so that the air between the fine perforated plate 1 and the rigid plate 2 is a spring and the air in the fine perforated plate 10 is a mass. Then, at the resonance frequency, when the air (mass) in the fine perforation 10 vibrates violently in the fine perforation 10, the sound energy is dissipated by the friction between the air in the fine perforation 10 and the inner wall of the fine perforation 10. As a result, a sound absorbing effect is obtained.

In this model, the design parameters of the sound absorbing mechanism 4 are the diameter of the fine perforation 10, the thickness of the back air layer (distance between the fine perforation plate 1 and the rigid plate 2), the thickness of the fine perforation plate 1, and the aperture ratio. There are four types (ratio of the total area of the fine perforations 10 to the area of the fine perforations plate 1). By changing these four types of parameters, it is possible to design the sound absorption target frequency, the sound absorption coefficient, and the sound absorption coefficient at a frequency in the vicinity of the sound absorption target frequency. In particular, by selecting appropriate parameters, it is possible to achieve a high sound absorption coefficient with a thinness (back air layer thickness) that is impossible with a normal sound absorbing material in sound absorption of low and medium frequencies.

On the other hand, the sound absorbing mechanism 4 may have an extremely low sound absorbing coefficient at a frequency slightly distant from the sound absorbing target frequency.

At this time, the diameter of the fine perforation 10 is set to 1 mm or less. Further, due to production restrictions, the diameter of the fine perforation 10 is set to be larger than the thickness of the fine perforation plate 1.

FIG. 4 is a cross-sectional view of a main part of a railway vehicle equipped with the sound absorbing mechanism according to the first embodiment of the present invention. In FIG. 4, the sound absorbing mechanism 4 including the fine perforated plate 1, the rigid plate 2, and the plurality of side plates 3 is the region (space) at the back of the luggage rack 150, that is, between the roof structure 130 and the side ceiling panel 145. It is arranged in the region where the heat insulating sound absorbing material 180 is enclosed. The inner part of the luggage rack 150 is the position of the antinode of the acoustic standing wave as shown in FIG. When the sound absorbing mechanism 4 is arranged at this position, the sound absorbing mechanism 4 can efficiently absorb the noise inside the vehicle at the target frequency.

Further, the inner part of the luggage rack 150 is at the position of the antinode of the acoustic standing wave, and at the same time, is also a position that is difficult for passengers to see. That is, by arranging the sound absorbing mechanism 4 in the back of the luggage rack 150, not only the sound standing wave is effectively absorbed, but also the passengers who do not visually like the fine perforated plate 1 of the sound absorbing mechanism 4 can be accommodated. Correspondence can also be taken.

As described above, the sound absorbing mechanism 4 is a kind of Helmholtz sound absorbing device, and exhibits a strong sound absorbing coefficient at the designed target frequency, but hardly absorbs sound at a frequency slightly away from that frequency. That is, if the above-mentioned design parameters change due to manufacturing variation, deterioration over time, or the like, the sound absorbing mechanism 4 may significantly reduce the sound absorbing coefficient at the target frequency. Further, even when the standing wave frequency is slightly changed due to the variation of the passenger cabin itself, the sound absorbing effect by the sound absorbing mechanism 4 is not so effective. In order to overcome this problem, the following configurations are adopted in the following embodiments.

5A and 5B are views of the sound absorbing mechanism according to the second embodiment of the present invention, FIG. 5A is a sectional view of the sound absorbing mechanism according to the second embodiment of the present invention, and FIG. 5B is an embodiment of the present invention. It is a front view of the sound absorption mechanism which concerns on FIG. In FIG. 5, the sound absorbing mechanism 4a includes a composite fine perforated plate 1a, a rigid plate 2, and a plurality of side plates 3, and is configured as a box (cube). The composite micro-perforated plate 1a is configured by connecting a plurality of divided micro-perforated plates 11, 12, and 13 in series with each other and integrating them. A rigid plate 2 is arranged on the back side of the composite fine perforated plate 1a, and the distance between the composite fine perforated plate 1a and the rigid plate 2 is constant between the composite fine perforated plate 1a and the rigid plate 2. A plurality of side plates 3 for keeping the surface plate 3 are arranged. Each of the divided type fine perforated plates 11, 12 and 13 is formed to have substantially the same size, and each of the divided type micro perforated plates 11, 12 and 13 is covered with a plurality of fine perforated plates 11a, 12a and 13a, respectively. It is formed over. The fine perforations 11a, 12a, and 13a have different diameters (diameters). The size is intermediate between the diameter of the hole and the diameter of the fine perforation 13a. Further, each of the fine perforations 11a in the split type fine perforation plate 11 is formed at a position slightly deviated from each of the fine perforations 12a in the split type fine perforation plate 12. Each of the fine perforations 12a in the split type fine perforation plate 12 is formed at a position slightly deviated from each of the fine perforations 13a in the split type fine perforation plate 13.

At this time, for example, when the target frequency (noise peak and the frequency of the acoustic standing wave) of the fine perforated plate 1 shown in FIG. 3 is 250 Hz, the target frequencies of the divided fine perforated plates 11, 12, and 13 are set to 250 Hz, respectively. It is designed for 220Hz, 250Hz and 280Hz. By using the composite type fine perforated plate 1a instead of the fine perforated plate 1, even if the target frequency varies in the actual product, it can be overcome and robust sound absorption is possible.

In addition, in FIG. 5, as the composite type fine perforation plate 1a, the one having three kinds of split type fine perforation plates 11, 12 and 13 was used, but as the fine perforation plate used for the composite type fine perforation plate 1a, 3 It is not limited to species, but three or more species are also possible. Further, the split type fine perforated plates 11, 12 and 13 can be configured to have different sizes from each other.

FIG. 6 is a cross-sectional view of the sound absorbing mechanism according to the third embodiment of the present invention. In FIG. 6, the sound absorbing mechanism 4b includes a composite fine perforated plate 1a, a rigid plate 2, a plurality of side plates 3, and a plurality of sill plates 31, and is configured as a box (cube). The composite type fine perforated plate 1a is configured by integrating a plurality of divided type fine perforated plates 11, 12, and 13, and each of the divided type fine perforated plates 11, 12, and 13 is separated by a threshold plate 31. Has been done. That is, the inside of the sound absorbing mechanism 4b is divided into three air layers (back air layers) by two threshold plates 31. The configurations of the divided type fine perforated plates 11, 12, and 13 are the same as those of the composite type fine perforated plate 1a shown in FIG.

By dividing the inside of the sound absorbing mechanism 4b into three air layers by each threshold plate 31, the spring constant of the above-mentioned spring (back air layer) can be obtained behind each of the divided type fine perforated plates 11, 12, and 13. It can be reliably generated. As a result, the composite fine perforated plate 1a shown in FIG. 6 has a sound absorption coefficient at each target frequency (sound absorption coefficient in each of the divided fine perforated plates 11, 12, 13) as compared with the composite fine perforated plate 1a of FIG. improves.

Since the composite fine perforated plate 1a is constructed by using a thin plate for the above reason, the strength of the composite fine perforated plate 1a can be increased by arranging a plurality of sill plates 31 on the composite fine perforated plate 1a. Can be done. Further, when the composite type fine perforated plate 1a itself vibrates, the energy dissipation of sound due to the vibration of the above-mentioned mass (air in the fine perforated) may decrease, that is, the sound absorption coefficient may decrease, but the threshold plate 31 is a composite type. It also has the effect of reducing the vibration of the fine perforated plate 1a itself and maintaining the designed sound absorption coefficient.

Various shapes of the split type fine perforated plate portions 11, 12, and 13 of the composite type fine perforated plate 1a can be considered, and examples thereof include a triangle, a quadrangle, and a hexagon.

FIG. 7 is a perspective view of the sound absorbing mechanism according to the fourth embodiment of the present invention. In FIG. 7, the sound absorbing mechanism 4c adopts a honeycomb structure in the sound absorbing mechanism 4b shown in FIG. 6, and has a plurality of composite fine perforated plates 1b1, 1b2, 1b3, 1b4, 1b5, 1b6, 1b7, 1b8. , A plurality of rigid plates 2 and a plurality of side plates 3 are provided to form a honeycomb-structured box (cube). The composite type fine perforated plate 1b1 is composed of a plurality of divided type fine perforated plates 11, 13 and 12, and the composite type fine perforated plate 1b2 is composed of a plurality of divided type fine perforated plates 12 and 14. The composite type fine perforated plate 1b3 is composed of a plurality of divided type fine perforated plates 11, 13 and 12, and the composite type fine perforated plate 1b4 is composed of a plurality of divided type fine perforated plates 12 and 14. The composite type fine perforated plate 1b5 is composed of a plurality of divided type fine perforated plates 13, 12, and 14, and the composite type fine perforated plate 1b6 is composed of a plurality of divided type fine perforated plates 11, 15. The composite type fine perforated plate 1b7 is composed of a plurality of divided type fine perforated plates 13, 12, and 14, and the composite type fine perforated plate 1b8 is composed of a plurality of divided type fine perforated plates 11, 15.

Each of the divided type fine perforated plates 11, 12, 13, 14, and 15 is formed in a hexagonal shape, and each boundary is separated by a sill plate 31 and a side plate 3, respectively. Further, each rigid plate 2 arranged on the back side of each of the divided type fine perforated plates 11, 12, 13, 14, 15 corresponds to each of the divided type fine perforated plates 11, 12, 13, 14, 15. Each is formed in a hexagonal shape. Further, a plurality of fine perforations having different diameters (diameters) are formed over the entire surface of each of the divided type fine perforation plates 11, 12, 13, 14, and 15.

At this time, one of the divided micro-perforated plates 11, 12, 13, 14, and 15 and the plurality of side plates 3 connected to one divided micro-perforated plate and 1 One rigid plate 2 arranged to face each other with one divided type fine perforated plate constitutes one honeycomb cell. Twenty honeycomb cells are formed in the sound absorbing mechanism 4c. In this case, since the target frequency is different for each of the split type fine perforated plates 11, 12, 13, 14, and 15, the target frequency can be designed to be different for each honeycomb cell, and the sound in a certain target frequency band can be robust. Can absorb sound. That is, the five types of split-type fine perforated plates 11, 12, 13, 14, and 15 can disperse the target frequency around the target frequency to perform robust sound absorption with a wider target frequency. Further, in this case, all the above four types of design parameters can be applied to the design of each honeycomb cell.

FIG. 8 is a cross-sectional view of the sound absorbing mechanism according to the fifth embodiment of the present invention. In FIG. 8, the sound absorbing mechanism 4d includes a fine perforated plate 1d having a plurality of fine perforations 10, a rigid plate 2, a plurality of side plates 3, and a plurality of sill plates 31, and is configured as a box (cube). To. The fine perforated plate 1d is arranged obliquely with respect to the rigid plate 2. In this case, a plurality of side plates 3 having different lengths are vertically divided between the fine perforated plate 1d and the rigid plate 2. The space surrounded by the fine perforated plate 1d, the rigid plate 2, and each side plate 3 is divided into three spaces (back air layers) by a plurality of threshold plates 31. The three spaces have different sizes (volumes) because the fine perforated plate 1d is arranged diagonally with respect to the rigid plate 2. At this time, even if the micro-perforated plate 1d has the same diameter (diameter) of each of the micro-perforated plates 1d formed in the micro-perforated plate 1d, the thickness of the air layer behind the micro-perforated plate 1d (three spaces). Since the volume of the cells is different, the target frequencies are slightly different in each cell corresponding to the three spaces. Therefore, by configuring the sound absorbing mechanism 4d including the fine perforated plate 1d, the size of the fine perforations (fine perforations 11a, 12a, 13a) can be changed like the sound absorbing mechanism 4b including the composite fine perforated plate 1a. The target frequency can be dispersed around the original target frequency, and as a result, robust sound absorption with a wider target frequency as described above can be realized.

FIG. 9 is a perspective view of the sound absorbing mechanism according to the sixth embodiment of the present invention. In FIG. 9, the sound absorbing mechanism 4e includes a fine perforated plate 1e, a rigid plate 2, a plurality of side plates 3, and a plurality of sill plates 31, and is configured as a box (cube). The surface of the fine perforated plate 1e is formed in a curved surface shape, and the fine perforated plate 1e is arranged obliquely with respect to the rigid plate 2. In this case, a plurality of side plates 3 having different lengths are separately arranged on the left and right between the fine perforated plate 1e and the rigid plate 2. The space surrounded by the fine perforated plate 1e, the rigid plate 2, and each side plate 3 is divided into nine spaces (back air layers) by a plurality of threshold plates 31. That is, the sound absorbing mechanism 4e is composed of nine cells c1 to c9. At this time, the sizes (volumes) of the cells c1 to c9 are designed to be different from each other, and the cell c5 in the middle is designed to absorb sound at the original target frequency. Further, the eight cells c1 to c4 and c6 to c9 around the cell c5 are designed to absorb sound at a target frequency slightly deviated from the target frequency of the cell c5. As a result, the sound absorbing mechanism 4e can realize robust sound absorption by slightly expanding the original target frequency.

FIG. 10 is a cross-sectional view of the sound absorbing mechanism according to the seventh embodiment of the present invention. In FIG. 10, the sound absorbing mechanism 4f includes a fine perforated plate 1f, a rigid plate 2, and a plurality of side plates 3, and is configured as a box (cube). The fine perforated plate 1f and the fine perforated plate 1g are arranged so as to face each other with the rigid plate 2 in between, and both ends of the fine perforated plate 1f and both ends of the fine perforated plate 1g are connected via the side plate 3, respectively. To. The fine perforated plate 1f is arranged inside the railroad vehicle 100, for example, and the fine perforated plate 1g is arranged facing the outside of the railroad vehicle 100. A plurality of fine perforations 10a are formed in the fine perforation plate 1f, and a plurality of fine perforations 10b having a diameter smaller than that of each fine perforation 10a are formed in the fine perforation plate 1g.

At this time, the space surrounded by the fine perforated plate 1f, the fine perforated plate 1g, and each side plate 3 is divided into a plurality of spaces (back air layers) by the rigid plate 2, and the spaces on both sides of the rigid plate 2 It has a structure that absorbs sound. That is, the fine perforated plate 1f can absorb sound in a specific target frequency band in the passenger compartment, and the fine perforated plate 1g can absorb sound in a specific target frequency band from the outside of the vehicle to the inside of the vehicle. it can. In the fine perforated plate 1f and the fine perforated plate 1g, the frequency band of the sound to be absorbed may be different from the same case. For example, when the size of the space on both sides of the rigid plate 2 is designed to be the same and the diameters (diameters) of the fine perforations formed in the fine perforation plate 1f and the fine perforation plate 1g are designed to be the same, the fine perforation plate is used. The frequency band of the sound to be absorbed can be made the same in 1f and 1g of the fine perforated plate. Further, when the size of the space on both sides of the rigid plate 2 is designed to be different and the diameters (diameters) of the fine perforations formed in the fine perforation plate 1f and the fine perforation plate 1g are designed to be different, the fine perforations are made. The frequency bands of the sound to be absorbed can be made different between the plate 1f and the fine perforated plate 1g.

FIG. 11 is a cross-sectional view of the sound absorbing mechanism according to the eighth embodiment of the present invention. In FIG. 11, the sound absorbing mechanism 4g includes a fine perforated plate 1h, a rigid plate 2, and a plurality of side plates 3, and is configured as a box (cube). The fine perforated plate 1h is arranged, for example, facing the outside of the railway vehicle 100, and the rigid plate 2 is arranged inside the railway vehicle 100. A plurality of fine perforations 10c are formed in the fine perforation plate 1h.

At this time, the fine perforated plate 1h is designed to absorb sound in a specific target frequency band outside the cabin. That is, in order to reduce the sound inside the vehicle, particularly the sound of the standing wave frequency in the cabin, the fine perforated plate 1h can absorb the sound before it enters the vehicle from the outside of the vehicle via the air propagation path.

FIG. 12 is a cross-sectional view of the sound absorbing mechanism according to the ninth embodiment of the present invention. In FIG. 12, the sound absorbing mechanism 4h includes a fine perforated plate 1 and a plurality of side plates 3, and is fixed to the lower surface plate 115a below the underfloor duct 115. At this time, the fine perforated plate 1 is arranged so as to face the outside of the vehicle, and the lower surface plate 115a below the underfloor duct 115 functions as a rigid plate of the sound absorbing mechanism 4h. Further, the underfloor duct 115 exists in the underframe portion B shown in FIG. 1, and is located below the antinode of the sound pressure of the standing wave in the underframe portion B shown in FIG.

In the railroad vehicle 100, the sound in the low to medium frequency range mainly enters the passenger compartment from the lower part of the railroad vehicle structure 105. Therefore, by arranging the sound absorbing mechanism 4h on the lower surface plate 115a at the lower part of the underfloor duct 115, it is possible to reduce the sound in the low to medium frequency range from entering the passenger compartment from the lower part of the railway vehicle structure 105 as air propagation sound. can do. That is, it is possible to reduce the noise in the cabin by absorbing the sound of the standing wave frequency in the cabin in the low to medium frequency range outside the cabin.

FIG. 13 is a cross-sectional view of the sound absorbing mechanism according to the tenth embodiment of the present invention. In FIG. 13, the sound absorbing mechanism 4i includes a fine perforated plate 1f and 1 g and a plurality of side plates 3 and is configured as a box (cube). The fine perforated plate 1f and the fine perforated plate 1 g are arranged so as to face each other. Then, both ends of the fine perforated plate 1f and both ends of the fine perforated plate 1g are connected via the side plate 3, respectively. At this time, the fine perforated plate 1f is arranged so as to face the inside of the vehicle, and functions as a rigid plate for the fine perforated plate 1g. The fine perforated plate 1g is arranged in a state of being directed to the outside of the vehicle, and functions as a rigid plate for the fine perforated plate 1f. That is, the sound absorbing mechanism 4i corresponds to the sound absorbing mechanism 4f shown in FIG. 10 from which the rigid plate 2 is removed, and the fine perforated plate 1 g is arranged to face the fine perforated plate 1f instead of the rigid plate 2. It is a substitute fine perforated plate. The fine perforated plate 1f can absorb sound in a specific target frequency band in the passenger compartment, and the fine perforated plate 1g absorbs sound in a specific target frequency band from the outside of the vehicle to the inside of the vehicle. Can be done.

14 is a cross-sectional view of the sound absorbing mechanism according to the eleventh embodiment of the present invention, FIG. 14A is a cross-sectional view of the sound absorbing mechanism in which the fine perforated plate faces the traveling direction of the train, and FIG. , It is a cross-sectional view of a sound absorbing mechanism in which the fine perforated plate is oriented in the direction opposite to the traveling direction of the train. In FIG. 14, the sound absorbing mechanism 4j includes a fine perforated plate 1, a rigid plate 2, and a plurality of side plates 3, and is configured as a box (cube). The fine perforated plate 1 and the rigid plate 2 face each other. Both ends of the fine perforated plate 1 and both ends of the rigid plate 2 are connected to each other via the side plate 3.

At this time, in the sound absorbing mechanism 4j shown in FIG. 14A, the fine perforated plate 1 is arranged so as to face the traveling direction X of the train. That is, the fine perforated plate 1 is arranged in a state where the fine perforated plate 1 shown in FIG. 3 is rotated by 90 degrees.

Further, in the sound absorbing mechanism 4j shown in FIG. 14B, the fine perforated plate 1 is arranged so as to face in the direction opposite to the traveling direction X of the train. That is, the fine perforated plate 1 is arranged in a state where the fine perforated plate 1 shown in FIG. 3 is rotated in the reverse direction by 90 degrees.

When the fine perforated plate 1 is arranged in the traveling direction X of the train or in the direction opposite to the traveling direction X of the train, when the fine perforated plate 1 is attached to the interior panel 140 or the luggage rack 150, It has the effect of making the fine perforations 10 difficult to see from passengers.

FIG. 15 is a cross-sectional view of the sound absorbing mechanism according to the twelfth embodiment of the present invention. In FIG. 15, the sound absorbing mechanism 4k includes a plurality of fine perforated plates 1f and 1 g, a rigid plate 2, and a plurality of side plates 3 and is configured as a box (cube), wherein the fine perforated plate 1f and the fine perforated plate 1 g are provided. , The fine perforated plate 1g and the rigid plate 2 are arranged to face each other, and both ends of the fine perforated plate 1f, both ends of the fine perforated plate 1g, and both ends of the rigid plate 2 are arranged. Are each connected via a side plate 3. That is, the fine perforated plate 1f and the fine perforated plate 1g are connected in parallel via each side plate 3. A plurality of fine perforations 10a are formed in the fine perforation plate 1f, and a plurality of fine perforations 10b having a diameter smaller than that of each fine perforation 10a are formed in the fine perforation plate 1g.

At this time, the rigid plate for the fine perforated plate 1 g is the rigid plate 2, but the fine perforated plate 1 g functions as a rigid plate for the fine perforated plate 1f. Further, the space surrounded by the fine perforated plate 1f, the fine perforated plate 1 g, and each side plate 3 is divided into a plurality of spaces by the fine perforated plate 1 g, and sound absorption is performed in the spaces on both sides of the fine perforated plate 1 g. It has a structure. When the fine perforated plate 1f is arranged so as to face the inside of the vehicle, sound absorption of a specific target frequency band in the cabin can be performed stepwise by the two back air layers. It is also possible to connect three or more fine perforated plates in parallel via each side plate 3. Further, as in the case of the sound absorbing mechanism 4f shown in FIG. 10, the frequency band of the sound to be absorbed in the fine perforated plate 1f and the fine perforated plate 1g may be different from the same case.

For example, when the size of the space on both sides of the fine perforation plate 1g is designed to be the same and the diameters (diameters) of the fine perforations formed in the fine perforation plate 1f and the fine perforation plate 1g are designed to be the same, the fine perforation is made. The frequency band of the sound to be absorbed can be made the same in the plate 1f and the fine perforated plate 1g. Further, when the size of the space on both sides of the fine perforation plate 1g is designed to be different and the diameters (diameters) of the fine perforations formed in the fine perforation plate 1f and the fine perforation plate 1g are designed to be different, the fine perforation plate 1g is fine. The frequency bands of the sound to be absorbed can be made different between the perforated plate 1f and the fine perforated plate 1g.

FIG. 16 is a cross-sectional view of the sound absorbing mechanism according to the thirteenth embodiment of the present invention. In FIG. 16, the sound absorbing mechanism 4 m includes a fine perforated plate 1, a rigid plate 2, a plurality of side plates 3, and a sound absorbing material 5, and is configured as a box (cube). The fine perforated plate 1 and the rigid plate 2 are , The sound absorbing material 5 is arranged in the space between the fine perforated plate 1 and the rigid plate 2, and both ends of the fine perforated plate 1 and both ends of the rigid plate 2 are side plates 3 respectively. Connected via.

At this time, the fine perforated plate 1 that mainly exhibits strong sound absorbing power in a specific target frequency band having low and medium frequencies and the sound absorbing material 5 that mainly exhibits sound absorbing power in a wide band of medium and high frequencies are combined. That is, when the fine perforated plate 1 is incorporated into the railway vehicle 100, the portion of the heat insulating sound absorbing material 180 may be scraped (see FIG. 4), but the sound absorbing material 5 is placed between the fine perforated plate 1 and the rigid plate 2. By putting it in the space of, the sound absorbing power of the original railway vehicle 100 can be secured at a minimum.

Although the sound absorbing material 5 is attached to the back surface side of the fine perforated plate 1, the sound absorbing material 5 can also be attached to the front surface of the rigid plate 2. It is also possible to embed the sound absorbing material 5 in the back air layer, which is the space between the fine perforated plate 1 and the rigid plate 2.

FIG. 17 is a cross-sectional view of the sound absorbing mechanism according to the 14th embodiment of the present invention. In FIG. 17, the sound absorbing mechanism 4n includes a fine perforated plate 1 and a rigid plate 2. That is, the sound absorbing mechanism 4n is configured as a sound absorbing mechanism without the side plate 3.

As described above, the side plate 3 is arranged for the main purpose of keeping the distance between the fine perforated plate 1 and the rigid plate 2 as designed. At this time, even if the side plate 3 is not provided, the fine perforated plate 1 can maintain the sound absorbing function in the designed target frequency band as long as the distance between the fine perforated plate 1 and the rigid plate 2 can be maintained as designed. it can. However, if there is no side plate 3 and the distance between the fine perforated plate 1 and the rigid plate 2 changes, the spring (back air layer) in the space between the fine perforated plate 1 and the rigid plate 2 The spring rigidity does not change and the sound absorption function does not disappear, but the sound absorption frequency and the sound absorption coefficient change.

Therefore, in the present embodiment, the side plate 3 is replaced with another object already existing in the railway vehicle 100. Further, for example, when the sound absorbing mechanism 4h is arranged below the lower duct 115 as shown in FIG. 12, the lower surface plate 115a of the underfloor duct 115 can be substituted as the rigid plate 2.

That is, from a different point of view, the sound absorbing mechanism 4n has four types of design parameters: the diameter of the fine perforation 10, the aperture ratio, the thickness of the fine perforation plate 1, and the distance between the fine perforation plate 1 and the rigid plate 2 ( There is a back air layer thickness), and the sound absorption frequency and sound absorption ratio of the sound absorption mechanism 4n are determined by four kinds of parameters. Therefore, the sound absorbing mechanism 4n does not necessarily require a box dedicated to the sound absorbing mechanism (a box constituting the cube) as shown in FIG. 3 (b), and at least one of the rigid plate 2 and the side plate 3 One can be replaced with the one already in the vehicle.

FIG. 18 is a cross-sectional view showing an example of the sound absorbing mechanism according to the fifteenth embodiment of the present invention, which is configured by combining various fine perforated plates. In FIG. 18, the sound absorbing mechanism 4p includes a composite type fine perforated plate 1a including split type fine perforated plates 11, 12, and 13, a plurality of side plates 3, and a rigid plate 2, and is configured as a box (cube). There is. The space surrounded by the divided type fine perforated plates 11, 12, 13 and the side plates 3 and the rigid plate 2 is divided into three spaces (back air layer) by two sill plates 31.

In the space surrounded by the split type fine perforated plate 11, the side plate 3, the rigid plate 2, and the sill plate 31, the split type fine perforated plates 11a, 11b, and 11c that divide this space into two spaces are arranged. Has been done. Each of the divided type fine perforated plates 11a, 11b, 11c is connected in series with each other, and is configured as a composite type fine perforated plate as a whole. The sound absorbing material 51 is arranged in the space surrounded by the split type fine perforated plate 11, the side plate 3, the divided type fine perforated plates 11a, 11b, 11c, and the threshold plate 31.

The space surrounded by the split type fine perforated plates 11a, 11b, 11c, the side plate 3, the rigid plate 2, and the sill plate 31 is divided into three spaces by the two sill plates 32, and the three spaces. Sound absorbing materials 51a, 51b, and 51c are arranged in each of the above.

In the space surrounded by the split type fine perforated plate 12, the sill plate 31, the rigid plate 2, and the sill plate 31, the split type fine perforated plate 12a, 12b, 12c, 12d that divides this space into two spaces. Is placed. The split type fine perforated plates 12a, 12b, 12c, and 12d are connected in series with each other, and are configured as a composite type fine perforated plate as a whole. The sound absorbing material 52 is arranged in the space surrounded by the split type fine perforated plate 12, the sill plate 31, the divided type fine perforated plates 12a, 12b, 12c, 12d, and the sill plate 31.

The space surrounded by the split type fine perforated plates 12a, 12b, 12c, 12d, the sill plate 31, the rigid plate 2, and the sill plate 31 is divided into four spaces by three sill plates 32, and 4 Sound absorbing materials 52a, 52b, 52c, and 52d are arranged in each of the spaces.

In the space surrounded by the split type fine perforated plate 13, the sill plate 31, the rigid plate 2, and the side plate 3, the split type fine perforated plates 13a and 13b that divide this space into two spaces are arranged. There is. The split type fine perforated plates 13a and 13b are connected in series with each other, and are configured as a composite type fine perforated plate as a whole. The sound absorbing material 53 is arranged in the space surrounded by the split type fine perforated plate 13, the sill plate 31, the split type fine perforated plates 13a and 13b, and the side plate 3.

The space surrounded by the split type fine perforated plates 13a and 13b, the sill plate 31, the rigid plate 2 and the side plate 3 is divided into two spaces by one sill plate 32, and the two spaces are divided into two spaces. , Sound absorbing materials 53a and 53b are arranged, respectively.

The split-type micro-perforated plates 11, 12, and 13 are configured as composite micro-perforated plates in the layer farthest from the rigid plate 2, and realize robust sound absorption in which the target frequency is slightly widened around the target frequency. The split type fine perforated plates 11a to 11c, the divided type fine perforated plates 12a to 12d, and the divided type fine perforated plates 13a and 13b are configured as composite fine perforated plates as a whole, and spread to the target frequency as well. It has a robust sound absorption. Of course, the divided micro-perforated plates constituting each composite micro-perforated plate do not have to be all different. Further, it is not always necessary to attach the sill plates 31 and 32 to each of the composite type fine perforated plates, and for example, the sound absorbing mechanism 4a shown in FIG. 5 may have a configuration without the sill plates 31 and 32. Further, as in the sound absorbing mechanism 4i shown in FIG. 13, a fine perforated plate can be used instead of the rigid plate 2.

The sound absorbing materials 51, 52, and 53 may be made of different sound absorbing materials or may be made of the same sound absorbing material. The same applies to other sound absorbing materials including the sound absorbing materials 51a, 51b, and 51c.

The combination of various fine perforated plates used in the sound absorbing mechanism 4p is merely an example, and at least one of the following configurations (1) to (4) can be adopted.

(1) As the fine perforated plate, a composite fine perforated plate is used. For example, like the sound absorbing mechanism 4a, a composite type fine perforated plate 1a composed of a plurality of divided type fine perforated plates 11, 12, and 13 is used. In other words, by combining a fine perforation plate with a certain target frequency with a fine perforation plate with a target frequency that is slightly shifted around the target frequency, the sound in the original target frequency band can be produced without being affected by product variations. A composite fine perforated plate that can absorb sound robustly is constructed. A case without the side plate 3 is also included here.

(2) As the fine perforated plate, a fine perforated plate facing a direction other than the inside of the vehicle is used. Since the fine perforated plate 1f of the sound absorbing mechanism 4f shown in FIG. 10 faces the direction inside the vehicle, a fine perforated plate facing in a direction different from that of the fine perforated plate 1f is used. The orientation is not limited to a specific angle.

(3) As the fine perforated plate, for example, a plate in which a plurality of fine perforated plates 1f and 1g are connected in parallel, such as the sound absorbing mechanism 4k shown in FIG. 15, is used.

(4) As the fine perforated plate, for example, as in the sound absorbing mechanism 4 m shown in FIG. 16, a fine perforated plate 1 having a sound absorbing material 5 in the back air layer is used.

At least one of the above (1) to (4) can be applied to a sound absorbing mechanism such as a sound absorbing mechanism 4 or a sound absorbing mechanism 4p.

Further, the embodiments are described in detail for explaining the present invention, and are not necessarily limited to those including all the configurations described. For example, the sound pressure distribution shown in FIG. 2 is merely an example of an acoustic mode of a standing wave in a cabin, and the present invention is not specified in this acoustic mode. When the sound absorption target is a sound mode of a standing wave in a different cabin, the sound absorption mechanism can be installed at the position of the belly of the sound mode. Further, the space inside the cube composed of the fine perforated plate (composite type fine perforated plate), the side plate, and the rigid plate has the same size or a different size depending on the threshold plate, the rigid plate, or the fine perforated plate. It can be divided into multiple spaces. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configurations of each embodiment with other configurations.

1 Fine perforated plate, 2 Rigid plate, 3 Side plate, 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4j, 4k, 4m, 4n, 4p Sound absorbing mechanism, 5 Sound absorbing material, 10 Micro perforations, 31, 32 sill boards, 115 underfloor ducts, 150 luggage racks

Claims (12)

A railroad vehicle with a passenger compartment
A sound absorbing mechanism including a micro-perforated plate having a plurality of micro-perforated plates and a rigid plate arranged opposite to the micro-perforated plate and reflecting sound passing through the micro-perforated plate is provided.
The sound absorbing mechanism is a railway vehicle with a sound absorbing mechanism, which is arranged at a position on the antinode of an acoustic standing wave in the vehicle interior. The railway vehicle with a sound absorbing mechanism according to claim 1.
The sound absorbing mechanism
A railway vehicle with a sound absorbing mechanism, characterized by having one or more side plates that are connected to the fine perforated plate and the rigid plate, respectively, and that maintain a constant distance between the fine perforated plate and the rigid plate. The railway vehicle with a sound absorbing mechanism according to claim 2.
The side plate
It is composed of a plurality of side plates that are connected to the fine perforated plate and the rigid plate, respectively, and cover the space between the fine perforated plate and the rigid plate.
A railway vehicle with a sound absorbing mechanism, wherein a cube is formed of each of the fine perforated plate, the rigid plate, and the plurality of side plates. The railway vehicle with a sound absorbing mechanism according to claim 3.
The sound absorbing mechanism
The air in the space between the fine perforated plate and the rigid plate is a spring, and the air in each fine perforated plate of the fine perforated plate has a sound absorbing action as a mass.
The sound absorption frequency band and sound absorption coefficient of the sound absorption mechanism are
A first parameter indicating the thickness of the fine perforation plate, a second parameter indicating the size of the fine perforation, a third parameter indicating the aperture ratio of the fine perforation, the fine perforation plate and the above. A railroad vehicle with a sound absorbing mechanism, which is specified by a fourth parameter indicating a combination of distances from a rigid plate. The railway vehicle with a sound absorbing mechanism according to claim 1.
The fine perforated plate is
Each of the plurality of divided type micro perforated plates is composed of a composite type micro perforated plate connected in series with each other, and each of the divided type micro perforated plates is formed with micro perforations having the same diameter or different diameters. A railroad vehicle with a sound absorbing mechanism. The railway vehicle with a sound absorbing mechanism according to claim 3.
The space in the cube composed of the fine perforated plate, the rigid plate, and each of the plurality of side plates is divided into a plurality of spaces of the same size or different sizes by one or more partition plates. A railroad vehicle with a sound absorbing mechanism, which is characterized by being The railway vehicle with a sound absorbing mechanism according to claim 1.
The sound absorbing mechanism
It has a plurality of side plates that are connected to the fine perforated plate and the rigid plate, respectively, and maintain a constant distance between the fine perforated plate and the rigid plate.
The fine perforated plate is
Each of the plurality of divided type micro perforated plates is composed of a composite type micro perforated plate connected in series with each other, and each of the divided type micro perforated plates is formed with micro perforations having the same diameter or different diameters.
A cube is formed by each of the composite fine perforated plate, the rigid plate, and the plurality of side plates, and the space in the cube is the same size or a plurality of different sizes depending on one or more partition plates. A railroad vehicle with a sound absorbing mechanism, which is characterized by being divided into spaces. The railway vehicle with a sound absorbing mechanism according to claim 1.
The sound absorbing mechanism
It has a plurality of side plates that are connected to the fine perforated plate and the rigid plate, respectively, and maintain a constant distance between the fine perforated plate and the rigid plate.
The micro-perforated plate is composed of a plurality of micro-perforated plates connected in parallel to each other via the side plate.
Each of the plurality of fine perforated plates connected in parallel
Each of the plurality of divided type micro perforated plates is composed of a composite type micro perforated plate connected in series with each other, and each of the divided type micro perforated plates is formed with micro perforations having the same diameter or different diameters.
A cube is formed by each of the composite fine perforated plates, the rigid plate, and the plurality of side plates, and the cube is divided into a plurality of spaces having the same size or different sizes by a plurality of partition plates. A railroad vehicle with a sound absorbing mechanism that is characterized by being The railway vehicle with a sound absorbing mechanism according to any one of claims 6, 7, and 8.
A railway vehicle with a sound absorbing mechanism, characterized in that a sound absorbing material is arranged in at least one of the plurality of spaces. The railway vehicle with a sound absorbing mechanism according to claim 2.
The side plate
It is composed of a plurality of side plates connected to the fine perforated plate and the rigid plate, respectively.
The fine perforated plate is
It is composed of a plurality of fine perforated plates connected in parallel to each other via the side plates with the rigid plate in between.
The plurality of micro perforations connected in parallel are formed with micro perforations having the same diameter or different diameters, respectively.
A cube is formed by each of the plurality of fine perforated plates and the plurality of side plates connected in parallel, and the space in the cube is divided into a plurality of spaces having the same size or different sizes by the rigid plate. A railroad vehicle with a sound absorbing mechanism, which is characterized by being The railway vehicle with a sound absorbing mechanism according to claim 1.
The sound absorbing mechanism
An alternative micro-perforated plate arranged to face the micro-perforated plate in place of the rigid plate is provided.
A railway vehicle with a sound absorbing mechanism, wherein the alternative micro-perforated plate is formed with a plurality of micro-perforations having the same diameter or different diameters as the micro-perforated plate formed on the micro-perforated plate. The railway vehicle with a sound absorbing mechanism according to claim 2.
The side plate
It is composed of a plurality of side plates connected to the fine perforated plate and the rigid plate, respectively.
The fine perforated plate is
It is composed of a plurality of micro-perforated plates connected in parallel to each other via the respective side plates, and one of the plurality of micro-perforated plates is located between the other micro-perforated plate and the rigid plate. Placed,
The plurality of micro perforations connected in parallel are formed with micro perforations having the same diameter or different diameters, respectively.
A cube is formed by each of the plurality of micro perforated plates connected in parallel, the rigid plate, and the plurality of side plates, and the space in the cube is the same size or different depending on the one micro perforated plate. A railroad vehicle with a sound absorbing mechanism, which is characterized by being divided into multiple spaces of different sizes.

Images